In a pneumococcal pneumonia animal model, vitamin D was shown to be involved in innate immunity; vitamin D upregulates toll-like receptor 2 (TLR2) and nucleotide-binding oligomerization domain 2 (NOD2) and induces antibacterial human neutrophil peptides and LL-37 that are involved in adaptive immunity. Here, NOD2 is linked to pneumococcal pneumonia.